Chapter 10 (section 10.12-10.16): microbiology mastering online HW

Which of the following conditions favors a lysogenic life cycle in bacteriophages? Having ssDNA. Having ssRNA. The presence of abundant hosts. A lack of host bacteria.

A lack of host bacteria.

A bacteriophage that lacks its proteinaceous capsid structure is also called a viroid.

False

Viroids infect only fungi.

False (can infect plants also)

Explain why viroids can only infect and damage plant cells, but not animal cells. Plant cells contain a RNA polymerase that can copy RNA can animal cells do not. Animal cells contain RNA polymerase that can copy RNA and plant cells do not. The genome of plant cells is made of RNA while animal cells have a DNA genome. Although both types of cells contain RNA, viroids recognize a specific receptor on the surface of plant cells.

Plant cells contain a RNA polymerase that can copy RNA can animal cells do not.

Prions defy our traditional understanding of pathogens, as they are composed only of proteins (no genomic information) in their infectious form. Identify the correct sequence of events potentially leading to a prion-induced infection in nervous system cells.

The very first step for the synthesis of any protein is transcription, synthesis of mRNA in the nucleus. Then mRNA is transported into the cytoplasm for translation, protein synthesis. Then proper assembly of protein in its native, active structure called folding. If folding is proper than protein will perform normal function and if misfolding of protein occurs it would be either non-functional or function abnormally. So correct sequence is- Transcription-->translation--> normal function-->PrPsc induced misfolding of Prpc-->abnormal function

When two different influenza viruses infect the same cell, their segmented genomes can undergo reassortment which will result in antigenic shift. loss of neuramidase. antigenic drift. loss of hemagglutinin.

antigenic shift. Example explanation: Explain the process of genetic reassortment in influenza viruses (type A), which have segmented RNA genomes. Explain how genetic reassortment can result in antigenic shift, and what this means. Explain how antigenic shift can enable flu viruses to infect new hosts.Explain why antigenic shift can lead to epidemic flu. In very serious cases of viral mutations, something known as antigenic shift occurs. This is a sudden and major change in the surface antigens of a virus. Antigenic shift occurs when two different strains of influenza virus simultaneously infect the same cell in your body and undergo a process called genetic reassortment. This is a process whereby two viruses mix and match parts of their genome.Since the genome is radically changed, so are the HA and NA proteins on the surface of the viruses that are coded for by this new genome.The change is so drastic that it can cause pandemics, or outbreaks of a disease, over large areas of land, such as multiple continents or even all over the world. That's because the virus is so new, barely anyone has any prior immunity to it, and a lot of people, therefore, end up getting sick.